1. Field of the Invention
The present invention relates to a method of forming a uniform nano-particle array on a large area substrate, and more particularly, to a method of forming a nano-particle array by convective assembly, and a convective assembly apparatus for the forming the same.
2. Description of the Related Art
Nano technology is used for arraying nano-particles particle size that are a few nanometers to several tens of nanometers in size on a large area with a uniform surface density. This core technology is very useful in various fields such as information storage devices, memory devices, lighting devices, opto-electronics devices, and the like. For example, the technology of arraying quantum dots, including semiconductor compounds, can be used for various kinds of displays such as lighting devices; and the technology of arraying metal particles such as Au, Ag and Fe is highly likely to be used in the fields of information storage or memory devices. Much research for producing nano-particle arrays is being conducted and in progress, but there are still lots of difficulties in actually producing nano-particle arrays in large quantities because it is the process that requires high precision and incurs high costs. An article in Advanced Functional Material 2005, 15, 1329-1335 to Kim et al. has disclosed a method of forming a nano-particle array by convective assembly. The nanoparticle array disclosed in the aforementioned reference is of the particle size of several hundreds of nanometers. The method of making such a large array is therefore not suitable for arrays particle size of nano-particles having a particle size from a few to several tens of nanometers. Specifically, in the aforementioned reference, high temperature dry air is injected into a colloidal solution to evaporate the colloidal solution and to cohere the included nano-particles. When the high temperature dry air is injected directly into the colloidal solution, the array of nano-particles splits due to the injection pressure and the surrounding turbulent flow of air caused by the injection pressure.